1. Field of the Invention
This invention relates to planetary gearing for automotive transmissions. In particular the invention pertains to a connection between a brake drum and planet pinion carrier of a planetary gearset.
2. Description of the Prior Art
In a planetary gear unit having at least one set of planet pinions and a drum member surrounding them, the planet carrier, which carries the planet pinions rotatably mounted on planet gear spindles, includes a larger diameter disc member with which it is drivingly connected to the open end of the drum member by way of a projection and recess connection. This connection is axially fixed by a securing element.
Securing means of this kind for a connection between a planetary gear unit and a drum member is known from German Offenlegungsschrift 21 24 009, wherein the drum member forms an inner drum to accommodate a multiplate clutch fitted to it. One part of a planetary gear unit is provided on its outer circumference with a tooth system and engages on the drum member in a corresponding tooth system, which also accommodates the lugs of the clutch plates. The connection is secured by stops and offsets formed by bending down the drum member, as shown in FIG. 5 of said German specification.
From German Offenlegungsschrift 22 27 555, in particular FIG. 1B thereof, a connection for a planetary gear unit comprising a planet gear set surrounded by a drum member is known wherein the drum member forms a brake drum for a brake band passing round it. A part of a planet carrier is provided on its outer circumference with a plurality of radial projections, which project into axial recesses in the open end of the drum member. The connection is made by a retaining ring snapped into an annular groove formed on the inside of the drum member.
Production of this annular groove is made relatively difficult and expensive by the axial recesses located at the free end of the drum member. Furthermore, adjacent the planet carrier and an adjoining component of the gear unit there is an axial thrust washer or an axial needle bearing, which in one known form has to be fitted onto the planet carrier.